Muscle-Specific Upregulation of Timeless Mediates Exercise-Induced Amelioration of Age-Related Circadian Rhythm Disruption and Cardiac Dysfunction in Drosophila

<title>Abstract</title> <p> The core genes of the circadian pathway, such as <italic>Timeless(Tim)</italic> , not only participate in the regulation of biological rhythms, but also play significant roles in DNA damage repair, chronic inflammation, and metabolism of cells. However, it remains unclear whether exercise can delay the age-related phenotypic degeneration by regulating muscle <italic>Tim</italic> gene. In here, we first carried out the expression regulation of muscle <italic>Tim</italic> gene in the <italic>Drosophila</italic> by constructing the <italic>Mhc-gal4/Tim-UAS</italic> system, and then subjected the flies to a 4-week endurance exercise intervention. The results showed that knockdown of the muscle <italic>Tim</italic> gene accelerated aging-related phenotypic deterioration in <italic>Drosophila</italic> , manifesting as increased nighttime activity, decreased climbing speed, elevated heart rate and reduced cardiac output, shortened time to hypoxic heart failure, and shortened lifespan. This is accompanied by reductions in muscle tissue levels of <italic>Clk</italic> gene, <italic>Sir2</italic> gene, <italic>PGC-1α</italic> gene, <italic>Mhc</italic> gene, MRCC-I protein, and SOD protein, along with a significant increase in ROS. Conversely, overexpression of the muscle <italic>Tim</italic> gene delayed aging-related phenotypic changes in aged Drosophila. Exercise not only effectively counteracts the acceleration of aging-related phenotypic deterioration caused by muscle <italic>Tim</italic> gene knockdown but also further delayed aging-related phenotypic changes in aged <italic>Drosophila</italic> on the basis of muscle <italic>Tim</italic> gene overexpression. In summary, this study highlights the role of the muscle <italic>Tim</italic> gene in the aging of skeletal muscles and the heart, as well as the relationship between exercise and the muscle <italic>Tim</italic> gene, providing strategies for the prevention and treatment of age-related diseases. </p>